A SIMPLE MODEL FOR THE PREDICTION OF PHASE SWINGS OBSERVED IN ACOUSTIC PROPAGATION DATA

In 1986, a propagation loss experiment was conducted in which a narrowband source moved away from two widely separated hydrophones located in shallow water. It was found that the relative phase between the signals received at the two hydrophones underwent rapid swings near the nulls of the pressure field. In the paper, a simple two-mode propagation model is derived that explains the source of these phase swings. In order to produce phase swings as large as those observed in the experimental data, it was necessary to introduce different bathymetries along the propagation paths to the two hydrophones.